Work continues on the identification and characterization of circulating immune complexes and aggregates in systemic lupus erythematosus and other connective tissue diseases. Particular attention is focused on cryoprecipitates, complexes which can be precipitated by the first complement component (Clq), and complexes which can be adsorbed to membrane receptors on Raji cells. Complexes are being elevated after digestion with pronase to determine residual material such as DNA. The role of immune complexes in stimulating both normal and sensitized lymphocytes is being evaluated. The effect of rheumatoid factor in modulating the effects will be studied during the coming year. A "third population" of lymphocytes has been well defined. Extensive studies are currently being carried out to evaluate the function of these "third population" or "L" cells. Characteristics of the lymphocyte membrane are being evaluated in detail to determine if there is any special property of lupus lymphocytes. Anti-lymphocyte antibody is being used as a probe to determine if there are any specific markers on SLE lymphocytes which might indicate the presence of a virus or viral remnant.